Antenna system



March M3, WM. R, VON OTTENTHAL.

ANTENNA SYSTEM Filed NOV. 9, 1939 Patented Mar. 18, 1941 UNITED STATES PATENT OFFICE ANTENNA SYSTEM Application November 9, 1939, Serial No. 303,509 In Germany November 9, 1938 1 Claim.

The present application constitutes an improvement relating to the copending application Serial No. 244,440, filed December '7, 1938, in the names of Walter Max Hahnemann and Ernst Kramar for System for landing aircraft assigned to the same assignee.

The above-mentioned copending application relates to a system for landing aircraft according to the glide path or slip-way principle, in which landing curves of constant field intensity to be followed by a descending airplane are produced by radiating a spatial radiation pattern and causing another radiated wave energy to intersect the spatial radiation pattern at such angle as to 15 establish points of constant field intensity on a locus of an inclined plane. The spatial radiation pattern produced for the above-mentioned purpose preferably comprises two regions of higher field intensities and an intermediate re-entrant 0 portion of lower field intensity within which an airplane is guided from the moment at which the landing descent is commenced until the moment at which it touches ground on the landing place. The guide beams thus produced fully com- 25 ply with the aeronautic requirements.

It is the object of this invention to provide an antenna system of simple structure capable of emitting radiation pattern involving the abovementioned proper-ties.

30 My invention will be more readily understood from the following description taken in conjunction with the accompanying drawing, in which Fig. 1 schematically shows the structure of an antenna system as proposed according to this in- 35 vention, while Fig. 2 embodies a radiation pattern as produced by the antenna system shown in Fig. 1.

Referring to Fig. 1, Di and D2 denote two dipoles spaced apart from one another at a distance equal to one operating wavelength. These 5 two dipoles are energized in phase opposition by a transmitter. However, the antenna currents supplied to the dipoles are of different magnitudes, the amplitude ratio being 11 /3, for example. The size and shape of the re-entrant portion of lower field intensity of the resulting radiation pattern shown in Fig. 2 may be varied by adjusting the ratio of the currents supplied to the dipoles DI and D2 in order to comply with the aeronautic requirements of the landing place 15 in question. A reflector comprising units RI and R2, respectively, is located behind the dipole Di and D2, respectively, at a distance of one-quarter of an operating wavelength. These reflectors are excited by radiation from the appertaining dipoles and act to intensify the effect of radiation therefrom in the desired direction.

What is claimed is:

An antenna system comprising two radiating dipoles spaced apart from one another at a dis- 5 tance equal to one operating wavelength, a reflector behind each of the said dipoles at a distance of one-quarter of an operating wavelength therefrom, and means for energizing the said dipoles by currents of opposite phase and. different 3 magnitude for producing a radiation pattern having two lateral regions of higher field intensity and an intermediate re-entrant portion of lower field intensity.

RUDOLF VON OTTENTHAL. 

